This question was created on May 02, 2007 by jdmiles.This question was last modified on May 02, 2007.

ANSWERS AND EXPLANATIONS

A) these neurons will synapse in the medulla

This answer is correct.

The fiber tract highlighted in red is the left fasciculus gracilis. This carries sensations of light touch, vibration, and proprioception from the more inferior portions of the body, such as the lower extremities. The cell bodies for these neurons are in the ipsilateral dorsal root ganglion. They ascend ipsilaterally until they reach the nucleus gracilis in the medulla, where they will synapse onto the second-order neurons. (See References)

B) these are fibers that carry sensations of light touch, vibration, and proprioception from the right side of the body

This answer is incorrect.

The fiber tract highlighted in red is the left fasciculus gracilis. This carries sensations of light touch, vibration, and proprioception from the more inferior portions of the body, such as the lower extremities. The cell bodies for these neurons are in the ipsilateral dorsal root ganglion. They ascend ipsilaterally until they reach the nucleus gracilis in the medulla, where they will synapse onto the second-order neurons. Sensations of light touch, vibration, and proprioception from the right side of the body are carried by the right fasciluls gracilis and cuneatus. (See References)

C) this is the fasciculus cuneatus

This answer is incorrect.

D) these are fibers that carry sensations of light touch, vibration, and proprioception from the upper extremities

This answer is incorrect.

The fiber tract highlighted in red is the left fasciculus gracilis. This carries sensations of light touch, vibration, and proprioception from the more inferior portions of the body, such as the lower extremities. The cell bodies for these neurons are in the ipsilateral dorsal root ganglion. They ascend ipsilaterally until they reach the nucleus gracilis in the medulla, where they will synapse onto the second-order neurons. Sensations of light touch, vibration, and proprioception from the upper body and extremities are carried by fibers in the fasciculus cuneatus. (See References)

E) the cell bodies of these neurons are in the contralateral dorsal root ganglion

This answer is incorrect.

The fiber tract highlighted in red is the left fasciculus gracilis. This carries sensations of light touch, vibration, and proprioception from the more inferior portions of the body, such as the lower extremities. The cell bodies for these neurons are in the ipsilateral dorsal root ganglion. They ascend ipsilaterally until they reach the nucleus gracilis in the medulla, where they will synapse onto the second-order neurons. (See References)